I really like how the missions are promoting you to progress through the game by requiring higher power rating decks.
What i dont like is that i have not noticed the rewards increase to reflect this, at least so far. Seems like its a steady 30k silver but in order to achieve the higher power level missions you need to spend a lot more.
The only reward "upgrading" seems to be the mercs but i guess they really couldn't just keep giving the same ones over and over (or could they?).
But this seems like a double edged sword as on the one hand its nice to have a few cards to start upgrading power level for the next missions.
on the other hand there's now a whole bunch of noobs running around with over weight cards in their decks and wondering why they keep loosing.
also they only last for 20 battles so make you come back to rent more (scratches arm).